Abstract: Cylindrical electrical assembly comprises a plug part and a receptacle part, each part consisting of a metallic shell and an insulating insert within the shell. The insert of the receptacle part has an integral hood which extends forwardly beyond the mating face of the receptacle insert and which receives forward portions of the plug insert. The shell of the receptacle part also has an integral hood which extends forwardly, and is radially spaced from, the hood of the insert. Forward portions of the plug shell are received between the hood of the receptacle insert and the hood of the receptacle shell. The internal surfaces of the hoods of the receptacle shell and the receptacle insert are each provided with keyways. These keyways receive integral keys on the plug shell and the forward portions of the plug insert.